Just now when I opened the OneDrive app on my iPhone I noticed on the Me Tab on top next to my account the app is also showing my other accounts which have nothing to do with my account. 3 more are showing, one is O365 trial I created but did not use my personal email address which is my main and only account I use on OneDrive and the other two are work related, again nothing to do with my personal account so why have they suddenly appeared? When I click on them,I get a message 'o add this account you need to enter your sign-in info' I've never used any of these accounts on my OneDrive iOS app.

They are separate accounts using separate emails. I might have accessed them form a Windows 7 PC but not all from the same Windows 8/10 PC. 2 of them are work accounts,definitely not accessed at all outside of work or on same PC.

None of them are, never were. Only thing I can think of is that at some stage I might have signed in with some of these accounts in the Office 365 admin iOS app but it was deleted some time back. Maybe that's the reason?